TWI866265B - Cell selection method - Google Patents

Abstract

Embodiments of the disclosure provides a cell selection method, including: during performing a cell selection operation on a plurality of reference base stations, obtaining a signal indicator and a network congestion indicator corresponding to each reference base station; and selecting a serving base station from the reference base stations based on the signal indicator and the network congestion indicator corresponding to each reference base station.

Description

Cell selection method

The present invention relates to a wireless communication technology, and in particular to a cell selection method.

After turning on, the terminal device (such as a mobile phone) will try to connect to the Internet. During the connection process, it will first measure the signal information of nearby detectable cells (or base stations) and select the most suitable cell for connection. This process is called cell selection.

After connecting to the network, the terminal device will continue to monitor the network status and perform cell selection again when appropriate. This process is called cell reselection.

According to the contents of relevant communication standards (e.g., 3GPP TS 38.304), it can be known that during the process of cell selection or cell reselection, the terminal device selects a suitable cell based on signal strength (e.g., the SrxLev parameter defined in 3GPP TS 38.304) and signal quality (e.g., the Squal parameter defined in 3GPP TS 38.304), as well as frequency priorities or radio access technology priorities (RAT_ priorities), and then connects.

However, although this selection method allows the terminal device to select a serving cell with high signal strength and good signal quality, the terminal device may not necessarily experience good service quality.

For example, when a cell is congested for some reason (such as serving too many end devices), the end devices it serves may experience lower data transmission speeds even when the signal strength and signal quality are high.

In view of this, the present invention provides a cell selection method, which can be used to solve the above technical problems.

The embodiment of the present invention provides a cell selection method suitable for a terminal device, including: when performing a cell selection operation on multiple reference base stations, obtaining a signal indicator and a network congestion indicator corresponding to each reference base station; and selecting a service base station from the multiple reference base stations based on the signal indicator and network congestion indicator corresponding to each reference base station.

The embodiment of the present invention provides a cell selection method suitable for a base station, including: providing a signal indicator and a network congestion indicator corresponding to the base station to a terminal device, wherein the signal indicator and the network congestion indicator corresponding to the base station allow the terminal device to perform a cell selection operation.

Please refer to FIG. 1 , which is a schematic diagram of a communication system according to an embodiment of the present invention. In FIG. 1 , a communication system 10 includes a terminal device 11 and a base station 12.

In different embodiments, the terminal device 11 may represent a user equipment (UE), a mobile station, an advanced mobile station (AMS), or a wireless terminal communication device. In addition, the terminal device 11 may be a mobile phone, a smart phone, a personal computer (PC), a notebook PC, a netbook PC, a tablet PC, a television, a set-top-box, a wireless data modem, a game console, a portable device, or a portable multimedia player.

In different embodiments, the base station 12 is, for example, a wireless network access point, an enhanced node B (eNodeB), an advanced base station (ABS), a macro-cell base station, a pico-cell base station or a remote radio head (RRH), a gNodeB (gNB), etc., but is not limited thereto.

As shown in FIG1 , the terminal device 11 includes a communication circuit 112 and a processor 114. In one embodiment, the communication circuit 12 may provide the terminal device 11 with a wireless access function by including at least a transmitter circuit, a receiver circuit, an analog-to-digital (A/D) converter, a digital-to-analog (D/A) converter, a low noise amplifier (LNA), a mixer, a filter, a matching circuit, a transmission line, a power amplifier (PA), one or more antenna units, and a local storage medium.

In some embodiments, the communication circuit 112 may be a component such as a protocol unit, which may support various wireless network communication protocols, such as WiFi HaLow, etc. In other embodiments, the communication circuit 112 may also support signal transmission of a global system for mobile communication (GSM), a personal handy-phone system (PHS), a code division multiple access (CDMA) system, a wireless fidelity (Wi-Fi) system, or a worldwide interoperability for microwave access (WiMAX), but is not limited thereto.

In addition, the processor 114 is coupled to the communication circuit 112 and can be a general purpose processor, a special purpose processor, a traditional processor, a digital signal processor, a plurality of microprocessors, one or more microprocessors combined with a digital signal processor core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit, a state machine, an advanced RISC machine (ARM) based processor, and the like.

As shown in FIG. 1 , the base station 12 includes a communication circuit 122 and a processor 124, and possible implementations thereof may refer to the communication circuit 112 and the processor 114, which will not be further described herein.

In an embodiment of the present invention, the terminal device 11 and the base station 12 can work together to implement the cell selection method proposed by the present invention, the details of which are described as follows.

Please refer to FIG. 2, which is a flow chart of a cell selection method according to an embodiment of the present invention. The method of this embodiment can be executed by the terminal device 11 and the base station 12 of FIG. 1. The following is a description of the details of each step of FIG. 2 with reference to the components shown in FIG. 1.

In step S222 , the base station 12 provides the signal indicator and the network congestion indicator corresponding to the base station 12 to the terminal device 11 .

In one embodiment, the signal indicator corresponding to the base station 12 includes signal strength (e.g., SrxLev parameter) and signal quality (e.g., Squal parameter). In addition, the network congestion indicator corresponding to the base station 12 may include the user network throughput determined by the base station 12. In one embodiment, the user network throughput of the base station 12 is, for example, the user-perceived IP throughput determined by the base station 12, but is not limited thereto.

In different embodiments, the base station 12 may use a statistical value (such as an average value) of the user perceived network throughput of all terminal devices served by the base station 12 as the corresponding user network throughput, but is not limited thereto.

In the first embodiment, the user network throughput of the base station 12 is, for example, the current user network throughput determined by the base station 12. For example, assuming that the user network throughput determined by the base station 12 at the tth time point (t is a time index) is a certain value, the base station 12 may use this value as the current user network throughput (in ), and Provided to the terminal device 11.

In the second embodiment, the user network throughput of the base station 12 is, for example, the future user network throughput predicted by the base station 12. For example, assuming that the current time point is the t-th time point, the future user network throughput is, for example, the user network throughput corresponding to a later time point. For ease of explanation, it is assumed below that the future user network throughput corresponds to the t+1-th time point, but it is only used for example and is not used to limit the possible implementation methods of the present invention.

In a second embodiment, the base station 12 may feed at least one historical user network throughput into a prediction model (denoted by M), wherein the prediction model M may predict the future user network throughput (denoted by express).

In a first variation of the second embodiment, the prediction model M may include a long short-term memory model. In this case, the future user network throughput It can be represented by: (1) , where is the above historical user network throughput, L is the time window, is the long short-term memory model.

From equation (1), we can see that the prediction model M can be used to predict the network throughput of L+1 historical users (i.e., ) and predict the corresponding network throughput as the future user network throughput , but is not limited to this.

In a second variation of the second embodiment, the prediction model M may include a regression model. In this case, the future user network throughput It can be represented by: (2) , where is the random error value, is a constant, is the regression coefficient. In one embodiment, For example, it is a Gaussian random variable with a mean of 0 and a standard deviation of σ, but it is not limited to this.

Accordingly, in step S212, when performing a cell selection operation on a plurality of reference base stations (including the base station 12, for example), the terminal device 11 obtains a signal indicator and a network congestion indicator corresponding to each reference base station.

In the embodiment of the present invention, the multiple reference base stations are, for example, base stations used to manage the cell to which the terminal device 11 currently belongs (for example, the current serving base station of the terminal device 11), or base stations used to manage neighboring cells of the terminal device 11, but are not limited thereto.

In this case, the signal indicators corresponding to each reference base station include signal strength (e.g., SrxLev parameter) and signal quality (e.g., Squal parameter), and the network congestion indicators corresponding to each reference base station include the user network throughput determined by each reference base station (e.g., the current user network throughput in the first embodiment). and/or the future user network throughput in the second embodiment ).

In one embodiment, the terminal device 11 in an idle state (e.g., RRC_IDLE state) or an inactive state (e.g., RRC_INACTIVE state) can obtain information such as intra-frequency cells, inter-frequency cells, and inter-RAT cells from the current serving base station and perform cell selection operations accordingly.

In the embodiments of the present invention, the so-called cell selection operation can be broadly understood to also include cell reselection operation, but is not limited thereto.

Next, in step S214, the terminal device 11 selects a serving base station from the reference base stations based on the signal indicators and network congestion indicators corresponding to each reference base station.

In one embodiment, the terminal device 11 may find at least one candidate base station from the reference base stations based on the signal indicators corresponding to each reference base station, wherein the signal indicators corresponding to each candidate base station meet a preset condition.

In one embodiment, for one of the reference base stations (hereinafter referred to as the first reference base station), the terminal device 11 can determine whether the signal strength corresponding to the first reference base station is not lower than the signal strength threshold value (e.g., 0dB) and whether the signal quality corresponding to the first reference base station is not lower than the signal quality threshold value (e.g., 0dB) to determine whether the first reference base station belongs to the above-mentioned candidate base station.

In response to determining that the signal strength corresponding to the first reference base station is not less than a signal strength threshold and the signal quality corresponding to the first reference base station is not less than a signal quality threshold, the terminal device 11 may determine that the signal indicator corresponding to the first reference base station meets the preset condition. On the other hand, in response to determining that the signal strength corresponding to the first reference base station is less than the signal strength threshold or the signal quality corresponding to the first reference base station is less than the signal quality threshold, the terminal device 11 may determine that the signal indicator corresponding to the first reference base station does not meet the preset condition, but is not limited thereto.

In short, the terminal device 11 can find one or more reference devices whose signal strength is not less than the signal strength threshold and whose signal quality is not less than the signal quality threshold as the candidate base station, but is not limited thereto.

Afterwards, the terminal device 11 may select a serving base station from the candidate base stations based on the network congestion indicators corresponding to the candidate base stations.

In one embodiment, the terminal device 11 may select one or more of the candidate base stations with the highest user network throughput as the serving base station, but is not limited thereto. For example, assuming that the base station 12 not only meets the above-mentioned preset conditions but is also the candidate base station with the highest user network throughput, the terminal device 11 may select the base station 12 as the serving base station, but is not limited thereto.

Afterwards, the terminal device 11 can correspondingly perform a subsequent connection procedure (such as a random access procedure) on the selected service base station (such as the base station 12) to connect to the selected service base station, but is not limited thereto.

In summary, the method proposed by the present invention allows the terminal device to select a base station with better signal strength, signal quality and network congestion indicators (such as the highest user network throughput) as a service base station, thereby avoiding selecting a base station with more congestion as a service base station. In this way, the terminal device can experience a better data transmission speed after performing the cell selection operation, thereby improving the user experience.

Although the present invention has been disclosed as above by the embodiments, they are not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the attached patent application.

10: Communication system 11: Terminal device 112, 122: Communication circuit 114, 124: Processor 12: Base station S212~S214, S222: Steps

FIG. 1 is a schematic diagram of a communication system according to an embodiment of the present invention. FIG. 2 is a flow chart of a cell selection method according to an embodiment of the present invention.

11: Terminal device

12: Base station

S212~S214,S222: Steps

Claims (14)

A cell selection method, suitable for a terminal device, includes: when performing a cell selection operation on multiple reference base stations, obtaining a signal indicator and a network congestion indicator corresponding to each of the reference base stations; and selecting a serving base station from the reference base stations based on the signal indicator and the network congestion indicator corresponding to each of the reference base stations, wherein in response to the terminal device being in an idle state or an inactive state, obtaining one of intra-frequency cell information and cross-frequency cell information from a current serving base station to perform the cell selection operation. As described in claim 1, the signal indicator corresponding to each reference base station includes a signal strength and a signal quality, and the network congestion indicator corresponding to each reference base station includes a user network throughput determined by each reference base station. As described in claim 2, the user network throughput is a current user network throughput determined by the first reference base station. The method as claimed in claim 2, wherein the user network throughput is a future user network throughput predicted by the first reference base station. As described in claim 1, the step of selecting the serving base station from the reference base stations based on the signal indicator and the network congestion indicator corresponding to each reference base station includes: Finding at least one candidate base station from the reference base stations based on the signal indicator corresponding to each reference base station, wherein the signal indicator corresponding to each candidate base station satisfies a preset condition; and selecting the serving base station from the at least one candidate base station based on the network congestion indicator corresponding to each candidate base station. As described in claim 5, the network congestion indicator corresponding to each reference base station includes a user network throughput determined by each reference base station, and the serving base station has a highest user network throughput among the at least one candidate base station. The method of claim 5, wherein the reference base stations include a first reference base station, the signal indicator corresponding to the first reference base station includes a signal strength and a signal quality, and the method further includes: in response to determining that the signal strength corresponding to the first reference base station is not less than a signal strength threshold value and the signal quality corresponding to the first reference base station is not less than a signal quality threshold value, determining that the signal indicator corresponding to the first reference base station meets the preset condition; and in response to determining that the signal strength corresponding to the first reference base station is less than the signal strength threshold value or the signal quality corresponding to the first reference base station is less than the signal quality threshold value, determining that the signal indicator corresponding to the first reference base station does not meet the preset condition. A cell selection method, suitable for a base station, comprises: providing a signal indicator and a network congestion indicator corresponding to the base station to a terminal device, wherein the signal indicator and the network congestion indicator corresponding to the base station allow the terminal device to perform a cell selection operation, wherein in response to the terminal device being in an idle state or an inactive state, one of intra-frequency cell information and cross-frequency cell information of the base station is provided to the terminal device, so that the terminal device performs the cell selection operation. As described in claim 8, the signal indicator corresponding to the base station includes a signal strength and a signal quality, and the network congestion indicator corresponding to the base station includes a user network throughput determined by the base station. As described in claim 9, the user network throughput is a current user network throughput determined by the base station. The method as claimed in claim 9, wherein the user network throughput is a future user network throughput predicted by the base station. The method as claimed in claim 11 further comprises: feeding at least one historical user network throughput into a prediction model, wherein the prediction model predicts the future user network throughput in response to the at least one historical user network throughput. The method of claim 12, wherein the prediction model comprises a long short-term memory model, and the future user network throughput is characterized by:

, where T _tL ,..., T _t is the at least one historical user network throughput, L is a time window, t is a time index, and f _λ (.) is the long short-term memory model. The method of claim 12, wherein the prediction model comprises a regression model, and the future user network throughput is characterized by:

, where c _t is the random error value, ε _t is a constant, φ _i is the regression coefficient, T _tL ,..., T _t is the at least one historical user network throughput, L is a time window, and t is a time index.

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